The present invention relates to an apparatus for precisely installing passive shim guide rails in the bore of an MR magnet.
Accurate placement of guide rails in MR magnets are important to help in precisely locating shim carrying drawers used to reduce field inhomogeneity and thereby permit a highly uniform magnetic field to be developed in the bore of the magnet. Magnet field inhomogeneity will distort the position information in the scan volume located in the magnet bore and degrade the image quality.
The guide rails, in addition to being spaced equally circumferentially apart to allow easy removal and insertion of the drawers preventing too much lateral motion, need to be correctly positioned in relation to the magnet. By having the rails installed in the same position in each magnet produced, the field map predicting the effect of a fixed size shim in each of the possible shim positions in the drawers can be used in all magnets of the same field strength and size.
It is an object of the present invention, to provide apparatus for installing guide rails in the bore of an MR magnet quickly and accurately.